PHYSICS CROSSWORD

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Across
  1. 4. the rate at which speed changes
  2. 8. sound waves with frequencies too high for humans to hear
  3. 9. the opposition to the flow of electric current
Down
  1. 1. rate at which work is done or energy is transferred
  2. 2. rays fast electrons released during radioactive decay
  3. 3. quantity of matter in an object
  4. 5. material that allows electricity to flow through
  5. 6. fundamental quantity measured in seconds
  6. 7. a thin strand of glass or plastic that transmits light signals for fast communication